The present invention relates to a new and improved construction of a controlled deflection roll--sometimes referred to in the art as a roll with bending or sag compensation--which is of the type comprising a stationary roll support or core, a roll shell rotatable about the stationary roll support and pressure or support elements located between the roll support and the roll shell. The ends of the roll shell are rotatably mounted upon guide elements, each guide element having a guide opening possessing two substantially parallel guide surfaces which are guided along corresponding guide surfaces of the roll support.
Such type controlled deflection roll is known to the art, for instance, from the commonly assigned U.S. Pat. No. 3,802,044, granted Apr. 9, 1974 and U. S. Pat. No. 3,885,283, granted May 27, 1975. With these state-of-the-art controlled deflection rolls the pressure or support elements, which may have the shape of hydraulic pistons, serve to press the roll shell against a counter roll.
Now for the lift-off of the roll shell from the counter roll, heretofore there were employed counter pistons, such as, for instance, disclosed and illustrated in the commonly assigned, U.S. Pat. No. 4,058,877, granted Nov. 22, 1977. These counter or lift-off pistons, which are constructed in the same manner as the pistons serving as pressure or support elements, during their operation bear against the inner surface of the roll shell. Since this inner surface, during the lift-off operation, in most cases rotates in relation to the roll support, provision must be made for lubricating the running or contact surfaces of the counter pistons. During hydrostatic lubrication of the running surfaces of pistons, according to the aforementioned U.S. Pat. No. 3,802,044, such requires a continuous throughput or feed of hydraulic oil.